linux-kernel - Re: [PATCH v4] PWM: atmel-pwm: add PWM controller driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 29 Sep 2013 18:02:37 +0800
From:	Bo Shen <voice.shen@...el.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
CC:	Thierry Reding <thierry.reding@...il.com>,
	<devicetree@...r.kernel.org>, <linux-pwm@...r.kernel.org>,
	<nicolas.ferre@...el.com>, <linux-kernel@...r.kernel.org>,
	<plagnioj@...osoft.com>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4] PWM: atmel-pwm: add PWM controller driver

Hi Alexandre,

On 9/28/2013 00:52, Alexandre Belloni wrote:
[snip]

>> +static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	int ret;
>> +
>> +	ret = clk_enable(atmel_pwm->clk);
>> +	if (ret) {
>> +		pr_err("failed to enable pwm clock\n");
>> +		return ret;
>> +	}
>> +
>
> This will increment clk->enable_count each time it is called.

Yes, that's true.

>> +	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
>> +
>> +	return 0;
>> +}
>> +
>> +static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	u32 val;
>> +
>> +	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
>> +
>> +	val = atmel_pwm_readl(atmel_pwm, PWM_SR);
>> +	if ((val & PWM_SR_ALL_CH_ON) == 0)
>> +		clk_disable(atmel_pwm->clk);
>> +}
>
> This will decrement clk->enable_count only once there are no pwm enabled
> anymore.  So in you enable more than one channel, you will never disable
> the clock. The simple fix is to always call clk_diasble, regardless of
> the state of the other channels.

Thank for point out this.

I see you have sent out a patch to fix it (however the other contents of 
your patch doesn't work). So, do you prefer I send out v5 patch to fix 
this? or you fix your patch at same time fix this issue?

Best Regards,
Bo Shen
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/